Non – Conventional Machining Processes

Non – Conventional Machining Processes : Modern machining methods are also named as advanced machining methods or non-conventional machining or non – traditional methods. With the development of technology, the scientists and technologists in the field of manufacturing are facing more and more challenges. Researchers in the area of material science are developing materials having high strength, hardness, toughness and other diverse properties such as super alloys,composites, HSTR (high strength temperature resistant) alloys and ceramics.  That is why, non-conventional machining processes are indeed essential for working with materials that are difficult to machine using conventional techniques. These advanced machining methods offer innovative and highly specialised ways of shaping, forming, or modifying materials. In these methods, there is no cutting of metal with the help of metallic tool having sharp cutting edges. Non-traditional machining methods remove excess material from a work piece without the direct contact and wear and tear associated with traditional cutting tools. These include a diverse range of techniques utilising electricity, heat energy, light energy, electro-chemical processes, chemical reactions, sound energy, and specialised mechanical forces to alter materials through removal, deformation, property changes, or plating.

The Need for Non-Traditional Machining:

The major reasons of development and popularity of modern machining methods are listed below:

(a) Need of machining newly developed metals and non-metals having some special properties like high strength, high hardness and high toughness. A material possessing the above mentioned properties are difficult to be machined by the conventional machining methods.

(b) Sometimes, it is required to produce complex part geometries that cannot be produced by following conventional machining techniques.

(c) Non-conventional machining methods also provide very good quality of surface finish which may also be an encouragement to these methods.

CLASSIFICATION / PRINCIPLE OF WORKING OF ENERGY : The principle of working is the base of type of energy used to remove the material. Classification along with the principle of working is described below:

1.  Use of Mechanical Energy : Mechanical energy is used for removing material from work piece. In this process, cutting tool with sharp edge is not used but material is removed by the abrasive action of high velocity of stream of hard, tiny abrasive particles. The particles are kept vibrating with very high velocity and ultrahigh frequency to remove the material.

2.  Electrical Energy : In this category of non-traditional machining, electrical energy is used in the form of electro chemical energy or electro-heat energy to erode the material orto melt and vaporized it respectively. Electro-chemical machining,electroplating or electro discharge machining are the examples work on this principle.

3.  Use of Thermal Energy : According to this principle, heat is generated by electrical energy. The generated thermal energy is focused to a very small portion of work piece. This heat is utilized in melting and evaporating of metal. The example based on this principle is electric discharge machining.

4.  Use of Chemical Energy : According to this principle of working, chemicals are used to erode material from thework piece. Selection of a chemical depends upon the work piece material.Example of this type of machining is electro-chemical machining. The same principle can also be applied in reversed way in the process of electro-chemical plating.

There can be one more way of classification of the non-conventional machining processes which is  mechanism of metal removal.

5. Abrasion and Shear : When small and hard metallic particles are made vibrating against the work piece to be machined, the material is removed by shear action and abrasion. These phenomenon take place in case of ultrasonic machining.

6. Chemical Ablation and Ionic Dissolution : This is the dissolution of work piece material into electrolyte solution(chemical) which takes place atom by atom. This happens in case of electro-chemical machining.

7. Vaporization by Spark Erosion : Concentrated heat is focused at a point of the work piece by electric spark which melts and evaporates the work piece material like electric discharge machining and Laser Beam Machining.

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